Immunological Causes of Infertility: Diagnostic Perspectives.

From an immunological perspective, infertility mechanisms encompass not only fertilization but also implantation, as well as both early and late pregnancy loss. Growing attention is being directed towards the influence of systemic disorders on reproductive outcomes. The immune system plays a fundamental and regulatory role in human reproduction. Immunological factors may affect multiple stages of this process, potentially justifying their inclusion in extended diagnostic pathways. The impact of autoimmunity and the presence of various antibodies on reproductive functions is discussed. Special attention is given to the immunomodulatory role of progesterone in reproduction and a state of impaired progesterone action-luteal deficiency. Endometriosis is also highlighted as a disorder both associated with infertility and underpinned by a strong immunological basis. The usefulness of assessing lymphocyte subpopulation balance, cytokine profiles, and Th1/Th2 immune response in the diagnostic work-up of infertility is addressed. Furthermore, the prospect for a role of local and systemic infections, subclinical inflammation and microbial colonization is shown. Tests applied in the evaluation of implantation and placental development disorders are discussed. Adequate immunological diagnostics and accurate identification of the underlying causes of infertility facilitate effective therapeutic strategies and can substantially increase the likelihood of achieving a successful pregnancy.